Circular Lists that are not lists?

[Thorsten Jolitz]

Hi List, 

in a parse-tree produced calling 'org-element-parse-buffer' in
org-buffer "tmp.org" I see that the first first-level headline is tagged
with a :CATEGORY attribute:

,---------------------------------------
| (headline (:CATEGORY #1=\"tmp\" ...))
`---------------------------------------

and that the other headlines in the parse-tree reference the attribute
value:

,-------------------------------
| (headline (:CATEGORY #1# ...))
`-------------------------------

except when a category is explicitly specified for them:

,------------------------------------------------
| (headline (:CATEGORY \"My Category Name\" ...))
`------------------------------------------------

Now ignore the Org-mode specific stuff, this question is really about
circular lists. 

This seems to be a case where circular lists are applied to strings -
should they rather be called circular sequences? 

How can I distinguish the three cases shown when mapping the parse-tree,
i.e. not on the textual level after printing the tree with (print-circle
t), but while mapping the nested list?

 - case 1 :: value defined #1=\"tmp\"

 - case 2 :: value referenced #1#

 - case 3 :: custom value without circular characteristics

?

When getting the property's values, they are all just strings ...

-- 
cheers,
Thorsten